The Epstein-Barr virus is associated with Burkitt's lymphoma, undifferentiated nasopharyngeal carcinoma, and a number of lymphoproliferative disorders. In vitro the virus can convert B lymphocytes into immortal lymphoblastoid cell lines which contain episomal viral genomes and express along subset of viral genes. The genome consists of unique short (12kb) and long (124kb) regions separated by a large 30kb tandem repeat assay (IR1) of a 3.1kb sequence. IR1 is the major physical feature of the genome, is transcribed during latency, encodes one of the latent nuclear antigens (EBNA4, also termed the EBNA-LP) and contributes leader exons to the mRNAs of all the EBNAs. The complex splicing pattern of latent transcripts through IR1 upon initial infection, during latency and after induction of virus production from a latent state will be investigated by a combination of direct Northern blotting with olignucleotides spanning splice junctions and polymerase chain reaction amplification of mRNA fragments using specific primers complementary to splice junctions and exons, and non-specific primers for 3' and 5' anchors. Since only small amounts of initial material are necessary for PCR, this technique will be developed for direct examination of tissue biopsies. The mechanism of regulation will be dissected in vitro by adding processing substrates. The information obtained will extensively map the IR1 transcription unit, develop in vitro models for examining control of IR1 transcript processing, and define the contribution of IR1 to in situ latency and lymphomagenesis. The techniques and reagents developed will be useful in further studies and may also be of diagnostic utility in assessing the pathogenesis of EBV associated lymphoproliferative disorders and neoplasms.